Gearbox Pump

ABSTRACT

What is proposed is a transmission pump ( 1 ), in particular a transmission oil pump of an automatic transmission, comprising a pump housing ( 2 ) and a pump cover ( 3 ) or an oil guide flange, with which in the case of a gear pump, the driving pump gear wheel ( 6 ) and, in the case of a vane cell pump, the vane cell wheel, is driven through a pump carrier ( 5 ) operatively connected to the pump drive shaft ( 4 ), whereas the pump carrier surface areas feature an inclination to the effect that the driving pump gear wheel ( 6 ) is led in an axial manner in the direction of the pump housing ( 2 ), and arrives at the structure at the pump housing ( 2 ).

The invention relates to a transmission pump, in particular atransmission oil pump of an automatic transmission, in accordance withthe preamble of patent claim 1.

From the state of the art, transmission pumps, particularly transmissionoil pumps, which are driven by the internal combustion engine and/or anelectric motor of the vehicle, are known. Pump systems that include twopumps, which are powered by the internal combustion engine and/or anelectric motor, are also known. In addition, variable displacementpumps, double-flow or multi-flow pump concepts along with pumps incombination with a pressure accumulator are known.

Under the state of the art, transmission pumps and compressors designedas gear pumps and vane cell pumps are constructed free of axial forces,which is to achieve a run of the pump gear wheels within the pumphousing that is as friction-free as possible.

Furthermore, producing the pump housing from cast iron and the pumpcover or oil guide flanges as light metal components from aluminum ormagnesium casting is also known from the state of the art.

The design of the pump gear wheels free of axial forces gives rise, in adisadvantageous manner, to a type of axial oscillation of such gearsand/or vanes, whereby the proportion of the pendulum swings in thedirection of the pump housing and the pump cover and/or oil guide flangeare nearly the same.

This axial oscillation of the pump gear wheels, which are usuallyproduced from steel or through sintering, in the direction of the lightmetal component, i.e. the pump cover or the oil guide flange, leads to ahigher wear of the inner surface of the pump.

DE 43 15 432 A1 discloses a conveyor unit for conveying fuel from astorage tank to an internal combustion engine of a motor vehicle with aconveying pump, which is formed as an internal gear pump and, as aconveyor link, features an internally toothed gear rim and a gear combedwith it, whereas the pumping chambers formed between the toothing arelimited, in the direction of the axis of rotation, on the one hand by acover plate and on the other hand by a guard plate, and in the coverplate form a suction opening and a pressure opening of the conveyorpump. In addition, the gear is pressed through a pressing elementagainst the guard plate, by which this is held in the structure at abase plate. This ensures that the gear rim and the gear are not able tocarry out any axial movements, which leads to the fact that pressurepulsations of the pump and disrupting noises are avoided.

With the known conveyor unit, it is also provided that the front surfaceof the guard plate sliding on the base plate and the front surface ofthe base plate are matched to one another to optimize the frictionconditions. The toothing of the conveyor link of the conveying pump canbe designed as helical gearing, by which an axial force acting on thegear rim arises, through which this is pressed against the guard plate.This is to achieve the advantage that, between the guard plate and thegear rim, a positive-locking connection is required only in direction ofrotation.

The design known from DE 43 15 432 A1 has the disadvantage that manycomponents, such as (for example) pressing elements and guard plates,are required to achieve axial stabilization.

The present invention has the task of specifying a transmission pump, inparticular a transmission oil pump of an automatic transmission, withwhich, in the operation of the pump, the pump gear wheels are led in anaxial manner in the direction of the pump housing without any increasedmanufacturing or assembly effort, by which a sliding of the pump gearwheels on the surface of the pump cover and/or the oil guide flange, andthus an increased wear of the pump cover and/or the oil guide flange, isprevented.

This task is solved by the characteristics of patent claim 1. Additionalarrangements and advantages under the invention arise from thesubclaims.

Accordingly, what is proposed is a transmission pump, in particular atransmission oil pump of an automatic transmission, comprising a pumphousing and a pump cover or an oil guide flange, with which in the caseof a gear pump, the driving pump gear wheel and, in the case of a vanecell pump, the vane cell wheel, is driven through a pump carrieroperatively connected to the pump drive shaft, whereas he pump carriersurface areas feature an inclination to the effect that, in the case ofa gear pump, the driving pump gear wheel and, in the case of a vane cellpump, the vane cell wheel, is led in an axial manner in the direction ofthe pump housing, and arrives at the structure at the pump housing.

Within the framework of an additional form of the invention, it can beprovided that, in the case of a gear pump, the toothing between thedriving and the driven pump gear wheel likewise features a targetedinclination, such that it is also the case that the driven pump gearwheel (for example, in the case of an internal gear pump, the ring gear)is led in an axial manner and arrives at the structure at the pumphousing.

In accordance with the invention, the pump housing is preferablydesigned as a cast iron housing, and the pump cover or oil guide flangeis preferably designed as a light metal component made of aluminum ormagnesium casting, for example.

The design under the invention prevents axial oscillation of the pumpgear wheels in the direction of the light metal component, resulting ina significant reduction in wear. Furthermore, in the operation of thepump, when axially viewed, a uniform air gap arises between the pumpgear wheels and the light metal component. In an advantageous manner,the degree of efficiency of the pump can thereby be increased.

Given the internal lubrication effect of cast iron, a purposeful, slightsliding of the pump gear wheels on the surface of the cast iron housingis not critical.

In the following, the invention is more specifically illustrated as anexample on the basis of the attached figures. The following is shown:

FIG. 1: A schematic sectional view of an internal gear pump designedaccording to the state of the art to illustrate the components relevantto the invention;

FIG. 2: an overhead view of an internal gear pump designed according tothe invention; and

FIG. 3; a sectional view along the line A-A from FIG. 2 and a sectionalview along the line B-B from FIG. 2.

The same reference signs designate the same components.

FIG. 1 shows a transmission pump 1, which features a cast iron housing 2and a pump cover 3 designed as a light metal component. The transmissionpump 1 designed as an internal gear pump is driven through a pump driveshaft 4, whereas, for this purpose, a pump carrier 5 operativelyconnected to the drive shaft 4 is provided, by which the rotary movementof the drive shaft 4 is transferred to the driving pump gear wheel 6,which in turn drives the driven pump gear wheel 7, which is designed asa ring gear, comprising an internal toothing. The transmission pump 1can be used as a transmission oil pump, for example.

In FIG. 1, the toothing between the driving and the drive pump gearwheel is provided with the reference sign 8. In a top view shown in FIG.2, the direction of rotation in the operation of the transmission pump 1is illustrated by the arrow 9.

In accordance with the invention and referring to FIG. 3, the upper partof which is a sectional view along the line A-A from FIG. 2, and thebottom part of which is a sectional view along the line B-B from FIG. 2,the pump carrier surface areas feature a targeted inclination, such thatthe driving pump gear wheel 6 is purposefully led in an axial manner inthe direction of the cast iron housing 2 and arrives at a definedstructure at the cast iron housing 2, which is illustrated by thereference sign 10.

In FIG. 3, the axial force that is generated along the main axis of thetransmission pump 1 is illustrated by the arrow 12, whereas the arrow 13indicates the direction of rotation in the operation of the transmissionpump 1. The resulting angle of inclination between the drive shaft 4 andthe pump carrier surface area of the pump carrier 5 is shown in theupper part of FIG. 3, and is provided with the reference sign α.

Furthermore, in accordance with the invention and referring to the upperpart of FIG. 3, when axially viewed, a uniform, stable air gap 11 arisesbetween the driving pump gear wheel 6 and the pump cover 3 designed as alight metal component.

In the example shown, the toothing 8 between the driving pump gear wheel6 and the driven pump gear wheel 7 likewise features a targetedinclination, such that the driven pump gear wheel 7 is also led in anaxial manner in the direction of the cast iron housing 2, by which itarrives at a defined structure 14 at the cast iron housing 2, as thebottom part of FIG. 3 illustrates. The angle of inclination of thetoothing 8 between the driving pump gear wheel 6 and the driven pumpgear wheel 7 is shown in the lower part of FIG. 3, and is provided withthe reference sign β. The axial force acting in the operation of thetransmission pump 1 is illustrated by the arrow 12.

As can be seen in the lower part of FIG. 3, when axially viewed, auniform, stable air gap 15 also arises between the driven pump gearwheel 7 and the pump cover 3 designed as a light metal component.

The invention prevents axial oscillation of the driving pump gear wheel6 and the driven pump gear wheel 7 in the direction of the pump cover 3designed as a light metal component, which, in an advantageous manner,results in a significant reduction in wear and an increase in theservice life of the transmission pump 1.

REFERENCE SIGNS

-   1 Transmission pump-   2 Housing made of cast iron-   3 Pump cover designed as a light metal component-   4 Pump drive shaft-   5 Pump carrier-   6 Driving pump gear wheel-   7 Driven pump gear wheel-   8 Toothing between the driving pump gear wheel 6 and the driven pump    gear wheel 7-   9 Direction of rotation-   10 Attachment of the driving pump gear wheel 6 at the cast iron    housing 2-   11 Air gap-   12 Axial force-   13 Direction of rotation-   14 Attachment of the driven pump gear wheel 7 at the cast iron    housing 2-   15 Air gap-   α Angle of inclination-   β Angle of inclination

1. Transmission pump (1), in particular a transmission oil pump of anautomatic transmission, comprising a pump housing (2) and a pump cover(3) or an oil guide flange, with which in the case of a gear pump, thedriving pump gear wheel (6) and, in the case of a vane cell pump, thevane cell wheel, is driven through a pump carrier (5) operativelyconnected to the pump drive shaft (4), characterized in that the pumpcarrier surface areas feature an inclination to the effect that, in thecase of a gear pump, the driving pump gear wheel (6) and, in the case ofa vane cell pump, the vane cell wheel, is led in an axial manner in thedirection of the pump housing (2), and arrives at the structure at thepump housing (2). 2-7. (canceled)